Many of today's two-party or multiple-party conversations are accomplished using some sort of wireless communication system such as the cellular data network or a wireless network transport media (e.g., WiFi, 2 G, 3 G, 4 G, etc.). In either case, a battery powered communication device (e.g., cell phone, smart phone, laptop computer, etc.) is typically used to access the wireless communication system. In terms of battery power requirements, communication devices use less battery power when accessing the cellular data network than when accessing one of the wireless network transport media. However, wireless network transport media provide (i) faster data transfer rates than the cellular data network, (ii) lower costs of usage since the airtime charges associated with the cellular data network do not typically apply, and (iii) lower latency compared to the cellular data network. Balancing these pros and cons of the cellular data network versus a wireless network transport media, more and more users of wireless communication device users are electing to use a wireless network transport media to carry on a wireless conversation.
The vast majority of battery-powered communication devices using a wireless network transport media can be classified as smart phones. As much as one-third of a smart phone's battery energy is consumed by its interface that accesses a wireless network transport media. That is, when this interface is “on” (i.e., fully powered in the case of 2 G/3 G/4 G) or “awake” (i.e., powered to support the device's Constantly Awake Mode (CAM) in the case of WiFi), the power requirements are substantially greater than when this interface is “off” (i.e., no power in the case of 2 G/3 G/4 G) or “asleep” (i.e., minimally powered to support the device's Power Save Mode (PSM) in the case of WiFi). Accordingly, it is important to “power” this interface only when necessary to conserve battery power for the communication device.
Studies have shown that periods of silence (i.e., no conversation audio from any party) comprise up to 60% of a typical human conversation. If a smart phone is “on” or in CAM during these periods of silence, the phone's interface is wasting battery power since data “blanks” are being sent/received over the wireless network transport media. It is clear that substantial battery power savings could be achieved if a smart phone's wireless network transport media interface was “off” or in PSM during most or all of the periods of silence. In the current state-of-the-art, most smart phones use a technique referred to as “adaptive PSM” to attempt to exploit the periods of silence in a conversation to save battery power. Briefly, adaptive PSM saves battery power by defaulting the smart phone to PSM and switching to CAM when traffic is observed on the wireless local area network (WLAN) being accessed. One drawback of adaptive PSM is that the transition time delay associated with mode switching (i.e., approximately 1.5 seconds) negatively impacts phone performance when periods of silence are small or when traffic arrives in clumps or bursts. A detailed description of adaptive PSM is presented by E. Rozner et al. in “Network-Assisted Power Management for WiFi Devices,” The Annual International Conference on Mobile Systems, Applications, and Services, 2010.